Thread gauge adapter for



' April 19, 1938. Y J. PILNICK THREAD GAUGE ADAPTER FOR MICROMETERS Filed July 9, 1934 Patented Apr. 19,1938

1'HBEAD GAUGE ADAPTER ma moaonmraas Jacob Pilni'ch, Cleveland, Ohio Application July 9, 1984. Serial No. 784,397

The present invention relates toan improved adapter for micrometer gauges permitting the.

use of the latter for measuring screw-threads. The ordinary micrometer caliper-does not lend itself to the accurate measurement of screwthreads since the engagement of the anvil and plunger of the caliper to the work cannot ordinariiy be maintained in positive or normal position on account of the fact that the irregular. sur face of the work is not adapted for engagement by the ordinary faces of the caliper. Since the contacting members of the caliper are generally lit plane faces they do not always take the same position with respect to the work. If the outer edge of the thread rests upon the anvil oi the I caliper the latter may pivot around that point of contact and thus prevent the movable plunger from resting in a normal position on the diametrically opposite portion of the thread. Furthermore, the depth to which the thread has been cut cannot be determined by the use of the normal contacting members of the caliper. I

It is an object of my invention to provide an adapter by which the size of the threads whichhave been out can be readily calculated from the measurement found on the conventional micrometer.

It is a further object of my invention to provide an adapter which will engage the sides of w the screw-threads being cut and from that engagement indicate the depth of the thread cut.

A still further object of my invention is to permit the depth of the thread to be indicated without requiring contact to be made at the bot tom of the groove between the threads.

Among the objects of my invention is to provide an adapter which may be adjusted along the thread to provide the desired clearance over the bottom of the thread and still maintain a fined position for the face that is to be engaged by the plunger of the micrometer.

It is also an object of my invention to provide an adapter of minimum length and a progressive adjustment equivalent to twice the normal length of the device.

The above and other features of my invention will be readily understood from the following de scription as illustrated on the accompanying drawing in which Fig. 1 is a side view of the adapter in simplest form;

Fig. 2 is a, top plan view thereof Fig. 3 is a left end view of Fig. 1;

Fig. 4 is a right end view of Fig. 1;

(or. sc -we) Fig. 5 is a side view of a modified form of the adapter;

Fig. 6 is a cross-section on the line 66 of Fig. 5 and in the direction of the arrows;

Fig. 7 is a cross-sectionon the line 1-1 of Fig. 5 and in the direction of the arrows;

Fig. 8 is an end view of the adapter as used in thread by means of a micrometer;

Fig. 9 is a left end view of Fig. 8;

Fig. 10 is a right end view or Fig. 8;

Fig. 11v is a side view of a modified form of this ada ter providing a maximum or range over a small near distance;

Fig. 12 is a left end view of this form;

Figs 1313 a cross-section on the line II-ii of Fig. 11;

the measurement oi an external buttress screw- I Fig. 14 is. a side viewof a screw thread meas ured by means of a caliper and the adapter;

.Fig; 15 is a side elevation of an internal caliper equipped with an adapter according to this invention and applied to an internal thread; Fig. 16 shows a similar view with a modified form of adapter; I a t Fig. 17 is an end view of the last n adapter;

Fig. 18 is a side view of the adapter shown in Fig. 15;, a

Fig. 19 is an and view thereof; v Fig. 20 is an end view thereof showing a 29 angle;

Fig. 21 is a side view of such an adapter de- I signed for internal buttress threads and Fig. 22 is an end view of the same.

The adapter consists essentially in a bar M of steel or similar hard material suitable to withstand wear under abrasion without material change in its form or dimensions. This bar as shown in'Fig. 3 has a cross-section substantially that of an equilateral triangle. The base it is a plane surface. Two faces Id and iii are inclined with respect to the base it at angles of 60. The edge formed by the intersection of the base 653- with the face it has been marked it for purposes of reference. The corresponding edge i'l is formed by the intersection of inclined face it with the base it.

The edge mat the apex of the bar is similarly formed by the intersection of the side faces i i and it. i

As will be more clearly shown in Fig. 1 th edge it extends about one-third the length of the bar it". From this point to the opposite end of the bar the edge I8 is progressively flattened.

that the bar form an adapter having a constant value of .200 inch this flattening varies progressively from zero to one-sixteenth inch. This flattening of the edge l8 results in the formation of a top face l9 progressively widening toward the right end of' the bar l2 and having a slight inclination with respect to the plane of the base I3.

By reference to Fig. 14 the utility and advantage of this adapter will be immediately apparent. The top face It is inserted within the thread between the adjacent sides of the latter bringing the side faces I and IS in contact with the sides of the screw-thread. The gauge may be moved longitudinally until its side faces make contact but there is the desired separation between the top face I! and the groove of the thread. In any position where the side faces I and [5 rest against the sides of the thread the adapter will provide allowance of a constant factor of .200 inch to be used with required depth of thread in calculating the corresponding final micrometer reading.

Fig. 5 illustrates the adapter in which the graduations in size are represented by a series of steps rather than a continuous slope. The angular relation of the opposite side faces of the adapter of Fig. 5 is shown in Fig. 6 while Fig. 7 indicates the appearance of the successive steps.

In Fig. 8 one side wall is perpendicular to the base as shown by Figs. 9 and 10 while the various successive graduations of the slope are marked onFig. 8 to agree with the stepped sequence of Fig. 5.

In Fig. 11 the adapter has been shown in a compact form. At one end there is provided a hand grip 20 while the opposite end 2| provides the desired special arrangements.

Referring to Fig. 13 it will be seen that the cross-section near the juncture between the hand grip and the adapter is generally triangular except that the apex has been modified by a slight flat top 24 similar to that shown at l9 in Fig. 2. One edge 22 which is oppositely disposed to the side I5 is analogous to the edge l8 opposite the base i3 in the first described modification. This edge 22 is, therefore, adapted to reach into the groove of a screw-thread in the same manner in which the edge l8 would be used.

The edge 23 which is opposite the inclined face H is flattened progressively toward the free end of the adapter starting from zero as shown in Fig. 13 to an adjustment in Fig. 12 of substantially half the maximum desired graduation or extent of variation in depth of the inclination.

The remaining edge 24 as shown in Fig. 13 has a flattened dimension substantially equal to the maximum of the edge 28. However, this increases toward the free end as shown in Fig. 12 to the maximum graduation desired. It will, therefore, be evident that the three edges of the adapter 2i provide all graduations found in the much longer bar i2.

As has already been said either face of the device may be usedas an anvil upon which the plunger 25 of the micrometer 26 rests. The opposite anvil 21 is in contact with the outer diameter of the screw-thread 28. The adapter l2 may then be moved along the thread until the faces I and I5 are properly seated against the side of the thread. By this seating it is meant that the side faces l4 and I5 will rest on opposite sides of the thread in lines of contact which are transverse to the adapter faces and which intersect the longitudinal axis of the screw. These lines of contact preclude the accidental engagement of the adapter solely on a single high point on the surface of the side of the screw thread. The reading of the micrometer gauge will then indicate the depth to which the thread has been cut.

The required depth of cut will be found by the use of suitable formulas involving only a knowledge of the constant value of the adapter I 2 and the graduated or standardized depth of cut. Thus the desired micrometer reading equals'the outside diameter of the screw required plus the difference between the constant of the adapter and the standard depth of a single thread of the screw. Expressed in another way and using data readily available in machinists tables, the root of the thread plus the single depth of thread plus the constant value of the adapter bar equals the desired reading of the micrometer for the appropriate thread standard. This also permits allowance for the slight undersize variation from standard which is used in cutting commercial threads. Illustrating this procedure by example, the following calculations are made from the appropriate tables:

%"--9 U. S. Standard Inch Root of thread .7307 Single depth of thread .0721 Adapter thickness .195

Thread gauge should reads. .9978

%"16 U. S. Standard Inch Root of thread .2936 Single depth of thread .0405 Adapter thickness .195

Thread gauge should read .5291

It will be obvious that where the required depth of the screw-thread is greater than the constant allowance of the adapter i2. the calculation will be accordingly modified as the above indicated difference is a negative quantity and thus reduces the micrometer reading required.

In Figs. 15 to 22 inclusive, I have shown the use of my invention for the measurement of the depth of internal threads. In this instance the adapter takes the form of a conical plug 28 having a spring sleeve 30 which is adapted to fit over the plunger 3| of an internal micrometer 32. The anvil 33 of the caliper rests upon the edge of the screw-thread 34 in the member 35. The conical adapter 29 has tapering lines of contact with the sides of the thread and the fixed allowance of the adapter will then permit the measurement of the depth of the screw-thread. Here again, the measurement of the screw-thread is obtained on a measurement based upon contact with the sides of the screw-thread rather than the depth of the groove.

In some instances it is desirable to supply a further abutment for the anvil 33 and one form has been shown in Figs. 16 and 17. Here the abutment takes the form of a prism 36 having a spring socket 31 for mounting on the anvil 33. In this way the micrometer 32 is maintained in a position perpendicular to the axis of the screwthreads.

In Figs. 18 and 19 the adapter 29 is similar to that shown in Fig. 15 except that the angularity of the cone has been changed from 60 to In some instances where a different angularity is called for, for example to handle screw-threads of 29 the form such as Fig. 20, is provided.

airaase A further form for a 15 buttress screw-thread is shown in Figs. 21 and 22 where the semi-com ical adapter 38 is mounted upon a spring backing 39.

The use of these forms of the adapter is selfevident. While this invention has been illustrated and describedin its preferred forms, still this is without limitation upon the invention other than as indicated by the scope of the following claims.

What I claim is:

1. An adapter bar for a gauge having a base and two faces all inclined each to the others, two edges being flattened to provide jointiya single progressive series of varying distances measured from the opposite face or base.

2. An adapter bar for a gauge having a base and two faces all inclined each to the other, two edges between intersecting faces being flattened to provide jointly a single progressive series of stepped distances measured from'the opposite face or base.

3. An adapter bar for a gauge having a hand grip at one end and three laces each inclined at 60 to the others, the edge between one pair of faces being cut away on a plane converging toward the end of the gauge and the edge between another pair of faces being cut away on a similar plane converging toward the said end, the amount of convergence of the second plane exceeding that of the first plane whereby the perpendicular distances measured from the second plane to the opposite face are progressive continuations of the variations provided by the perpendicular distances measured-from the first plane to the face opposite thereto.

4. An adapter bar for a gauge having a hand grip or handle and a work member extending from one end of the handle, said work member having three faces all inclined each to the others,

-,two edges between intersecting faces being fiattened to provide jointly a single progressive series of variable distances measured from the opposite face.

JACOB PILNICK. 

